1. Field of the Invention
The present invention generally relates to an optical integrated circuit element package, and more particularly relates to an optical integrated circuit element package with ball grid array.
2. Description of the Related Art
With the progress of the photo-electric technology, more and more photo-electric devices (e.g. light emitting devices or photosensitive devices) have been wildly used in a variety of optical product such as scanners, computer code bar readers, digital communication systems and others. In typical photo-electric applications, a photo-electric device in the form of integrated, circuit chip is disposed on a package having a sealed transparent window. Light beams pass through and into the sealed transparent window according to optical theory such that the photosensitive device can detect optical signals, or such that the light beams generated by light emitting device emit out through the window.
In the prior art, there have been many photo-electric device packages with respect to the form of integrated circuit chip. For example, U.S. Pat. No. 6,051,848 entitled xe2x80x9cOptical device packages containing an optical transmitter diexe2x80x9d issued to Webb on Apr. 18, 2000, has disclosed an optical device including an optical transmitter die and a package having mold material which encapsulates the optical transmitter die. However, the package manufacturing process generally uses conventional method including die attaching, wire bonding, molding and lead-bending, which therefore needs high cost, large space and much time in such package manufacturing process.
Further, it has been concerned how to readily and effectively dissipate the heat generated by the integrated circuit chip from the package. Also, in order to meet the requirement of electronic unit of low profile, the multichip module with higher density has become current trend for developing the package.
Therefore, there exists a need for the optical device package manufacturer to provide an optical device package with satisfactory low profile and low manufacturing cost, as well as able to provide semiconductor component with high-density fabrication.
It is an object of the present invention to provide an optical integrated circuit element package providing satisfactory low profile, high-density fabricated structure, good heat-dissipated ability, and low manufacturing cost.
It is another object of the present invention to provide a process for making optical integrated circuit element package wherein the package provides satisfactory low profile, high-density fabricated structure, good heat-dissipated ability, and low manufacturing cost.
In order to achieve the objects mentioned hereinabove, the present invention provides an optical integrated circuit element package comprising: a substrate having a plurality of solder balls disposed on one surface of the substrate, a plurality of bonding pads electrically connected to the solder balls, a cover attached to the other surface of the substrate, and a cavity to expose the cover; an upper chip provided with a plurality of bumps and adhered to the exposed cover in the cavity by a thermal gap fill; a lower chip having a plurality of bonding pads electrically connected to the plurality of bumps of the upper chip and having a plurality of bumps electrically connected to the plurality of bounding pads of the substrate; an optical-transparent underfill disposed between the lower chip and the upper chip; and a sealing compound hermetically seals the space between the lower chip and the substrate.
The present invention further provides a process for making an optical integrated circuit element package wherein the process comprises following steps: providing a substrate having a plurality of solder balls disposed on one surface of the substrate, a plurality of bonding pads electrically connected to the solder balls, a cover attached to the other surface of the substrate, and a cavity to expose the cover; providing an upper chip provided with a plurality of bumps; providing a lower chip having a plurality of bonding pads and a plurality of bumps; connecting the upper chip to the lower chip and electrically connecting the plurality of bumps of the upper chip to the plurality of bonding pads of the lower chip; filling the space between the lower chip and the upper chip with an optical-transparent underfill; connecting the lower chip to the substrate and electrically connecting the plurality of the bumps of the lower chip to the plurality of bonding pads of the substrate, and filling the space between the upper chip and the cover with a thermal gap fill.
As mentioned above, the optical element package according to the present invention is a thermo enhanced ball grid array package. The chip having the optical element directly contacts a heat-sinking cover by means of the thermal gap fill, thereby providing a fast heat-dissipating path. Furthermore, in the package according to the present invention, the chip having the optical element is packaged by the flip chip method such that the wire bonding process is eliminated so as to decrease manufacturing cost and to achieve high-density package.